Liberal leader Justin Trudeau stops to look at Chinese artist Yue Minjun's "A-mazing Laughter" statues while on his way to a meet and greet with people on the street near English Bay in Vancouver, B.C., on Thursday July 25, 2013.

Liberal Leader Justin Trudeau's admission that he smoked marijuana after being elected as an MP has reignited a debate about Canada's drug laws.

Mr. Trudeau revealed Thursday that he used pot three years ago. He won a seat in the Commons in the 2008 election.

"We had a few good friends over for a dinner party, our kids were at their grandmother's for the night, and one of our friends lit a joint and passed it around. I had a puff," he told the Huffington Post website.

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When reporters asked Mr. Trudeau about it Thursday in Quebec City, he expressed no regrets.

"No, it wasn't a mistake," he said. "… I've never tried other types of hard drugs. I am not a consumer of marijuana, but, yes, I've already tried it. I used it – maybe five or six times in my life."

Mr. Trudeau said he believes public opinion has moved on and he is confident Canadians will judge him less harshly than his political opponents.

Mr. Trudeau had expressed reservations about loosening up Canada's marijuana regime in the past but now says his position has "evolved."

And he takes that position as his party and the NDP fight to capture the progressive side of the political spectrum in the next two years – with the New Democrats now saying they will consider whether to shift their current policy in favour of decriminalization to outright legalization.

His stand has put the Liberal Party on a collision course with the Conservative government on the road to the 2015 election. The Tories are solidly against legalizing or decriminalizing marijuana and have pushed for tougher sanctions.

"By flouting the laws of Canada while holding elected office, he shows he is a poor example for all Canadians, particularly young ones," Mr. MacKay said in a statement.

The debate around Canada's marijuana laws has taken on new momentum this summer, with Canada's police chiefs saying this week that they want to end the practice of criminally charging every person found with small amounts of marijuana, and instead give officers the option of issuing tickets.

In addition, the NDP said Thursday it will review its long-held policy of promising to decriminalize marijuana possession, meaning Canadians would not be charged criminally for possession, but might still be ticketed or fined.

NDP justice critic Françoise Boivin told The Globe and Mail she has spoken with party leader Thomas Mulcair and the New Democrats' position on marijuana will be on the agenda when the caucus meets next month in Saskatoon.

Ms. Boivin said the decision to review the NDP policy of decriminalization is driven primarily by recent referendums in Colorado and Washington in favour of legalization, rather than the attention Mr. Trudeau has received for announcing he now supports legalization.

"We're not shutting the door to legalization," she said. "I like our position … but let's also continue the discussion and do a real serious study."

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Ms. Boivin, a former Liberal MP, said Mr. Trudeau has been inconsistent, voting in favour of stiffer penalties related to marijuana and previously supporting decriminalization.

Mr. Trudeau's admission, as the party continues to stress openness and transparency, could also be viewed as an election strategy that attempts to exploit a generation gap in Canadian politics.

The Liberal stand is likely appeal to younger voters, who are more socially liberal on all issues than older voters. But the young are also less likely to vote. In the last federal election, overall turnout was just 61 per cent. For Canadians aged 18-24 it was 39 per cent; for those aged 25-41 it was 45 per cent.

Ekos pollster Frank Graves said marijuana will not be a deciding issue for voters. However, he predicted Mr. Trudeau's stand will likely help him because public support for legalization is on the rise.

"It's not a ballot-box issue for most people," he said. "But there's considerably more upside than downside."

Mr. Graves added that decriminalization has strong support as well, so there's no clear political motivation for the NDP to support legalization.

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"I think that might look like sort of, 'Me too,' so I think they're probably fine with where they are," he said.

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